Priming device for igniting the main charge of a missile



March 8,1966 5. H. o. SIMMONS 3,238,877

PRIMING DEVICE FOR IGNITING THE MAIN CHARGE OF A MISSILE Filed April 27, 1964 ZNVENTOR BJQ'k/V HERMAN OLOF S/MMOALS A r TDRNE Y5 United States Patent ice 3,238,877 PRIMING DEVICE FOR IGNITING THE MAIN CHARGE OF A MISSILE Bjorn Herman Olof Simmons, 'Karlskoga, Sweden, as-

signor to Aktiebolaget Bofors, Bofors, Sweden, a corporation of Sweden Filed Apr. 27, 1964, Ser. No. 362,884 Claims priority, application Sweden, June 28, 1963, 7,196/ 63 6 Claims. (Cl. 102-70) The present invention relates to a device for igniting the main charge of a missile by hot gases generated by igniting a priming charge.

The main charge of the missile may be a luminous or illuminating charge, that is a light-generating charge, as used for instance in star shells, a propellant charge as used in rockets or any other charge of the type which is ignited by hot gases genera-ted by a priming charge and which, in turn, generates heat when ignited.

A problem common to all missiles of the general kind above referred to is to effect a rapid and substantially uniformly distributed ignition of the main charge by the priming charge upon ignition of thelatter.

Another problem common to all missiles of the general kind above referred to is to maintain the weight and the overall dimensions of all secondary components of the missile such as the priming charge, that is, of components which do not participate in the ultimate function of the missile, such as the priming charge. It has been attempted to provide as priming charge comparatively 3,238,877 Patented Mar. 8, 1965 FIG. 2 is a perspective View, partly in section, of the device proper on an enlarged scale, and

FIG. 3 is an exploded view of the device.

Turning now to the figures in detail, FIG. 1 shows a shell or projectile 1 with afuze 2 in its nose cone. The main charge such as a combustible luminous composition 3 is enclosed in a casing 4 which, in turn, is placed in the outer shell of the missile. The composition of the main charge should be visualized as being conventional and does not constitute part of the invention, provided only that the main charge 3 is ignitable by hot gases and in turn generates heat when ignited. Many suitable compositions of thiskind are well known in the art.

Casing 4 is headed over at its rim to form a flange 5 for retaining a circular disk 6. A spacer ring 11 between disk 6 and the top surface 3a of the main charge is provided to define a narrow, circular space 13 between the bottom side of disk 6 and the top side of charge 3. A boss 7 rises from the center portion of the disk. The boss is hollow to form a priming hole 9 communicating with space 13. An'annular priming charge 8 of suitable and conventional composition is inserted into the cavity small quantities of the so-called powder pellet type. However, it has been found that primary charges of this kind are not very effective. In some instances, in particular for the ignition of light generating compositions, it is desired to obtain a Widely distributed and substantially instant ignition of the pyrotechnical main charge. Small quantities of powder, either of the pellet type or any other suitable type, tend to effect an ignition of the main charge in small localized areas or spots only. It has also been attempted to provide large and consequently more voluminous priming charges. Such large priming charges result obviously in an undesirable increase in the total weight and volume of the missile and even so they have been found to be ineffective as they tend to produce an uneven ignition.

It is a broad object of the present invention to provide a novel and improved device for igniting the main charge of missiles of the general kind above referred to, which device effects a simultaneous ignition of substantially the entire surface of the main charge exposed to the action of the device without markedly increasing the total volume and weight of the missile.

A more specific object of the invention is to provide a novel and improved device for igniting the main charge of missiles of the general kind above referred to, which device distributes the hot gases generated upon ignition of the priming charge substantially over the surface of the main charge exposed to the hot gases, thereby effecting a substantially simultaneous ignition of said surface.

Other and further objects, features and advantages of the invention will be pointed out hereinafter and set forth in the appended claims constituting part of the application.

In the accompanying drawing a preferred embodiment of the invention is shown by way of illustration and not by way of limitation.

In the drawing:

FIG. 1 is a perspective view of an illuminating shell such as a star shell equipped with an igniting device according to the invention.

of. bossv 7. Disk -6 includes a ring of circumferentially spaced apertures 10 preferably placed concentric with priming hole 9. The diameter of the ring of apertures is such that the ring is close to the outer periphery of disk 6 and particularly to the inner perimeter of flange 5. The outer rim of spacer ring 11 coincides substantially with the outer diameter of disk 6 and the inner rim of the ring is outside the outer circle defined by holes 10.

The device as hereinbefore described, functions as follows:

The priming charge 8 is ignited through its priming hole 9 upon activation of fuze 2 in a manner not shown in detail but well understood in the art. The flame and the hot gases now generated by priming charge 8 escape to a small extent through priming hole 9 but the large portion of the hot gases flows outwardly within space 13 as defined by surfaces 3a and 12 and escapes through apertures 10 as it is indicated in FIG. 3 by outwardly pointing arrows. As a result, the hot gases or flames generated by the priming charge come in intimate contact with substantially the entire surface 3a within the area encircled by spacer ring 11 and thus cause substantially simultaneous ignition of this area.

The circumferential spacing between aperture 10 in the disk and the disk material itself are such that the hot gases of the priming charge will not burn or otherwise destroy the disk so that the disk will remain substantially intact even after the priming charge has burned completely. However, the ignition of the main charge 3, such as a luminous composition, results in the generation of a more intense flow of heat and such intensified flow will destroy the disk material between adjacent apertures 10. As a result, the inner portion of the disk as defined by the ring of apertures 10 will become separated from the remaining outer ring of the disk, aided by reinforcement of the outer disc ring flange 5 and spacer ring 11.

As a result, the inner intact portion of the disk is now released from casing 4 and will be thrown out of position. The casing 4 containing the main charge is also separated from the outer shell of the missile by means not shown as being not essential for the understanding of the invention but well known in the art.

As it is evident from the previous description, the device of the invention when applied to illuminating missiles has the advantage that the full luminous intensity of the missile is obtained practically immediately upon ignition of the composition 3. Obviously, it is of great importance for missiles such as star shells to utilize to the fullest extent the illuminating capability of the charge.

As initially stated, the principle of the invention can be applied to other missiles also such as rockets, or wherever a rapid ignition of a main charge is essential.

The function of the device for all types of missiles is automatically and substantially improved when the missile is fired from a rifled barrel to impart a spin to the missile during its trajectory. As it is evident, such spin will substantially increase the rate of flow of the hot gases within space 13.

While the invention has been described in detail with respect to a certain now preferred example and embodiment of the invention, it will be understood by those skilled in the art, after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it in intended therefore to cover all such changes and modifications in the appended claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A device for igniting the main charge of a missile, said device comprising a casing open at one end and containing the main charge to be ignited, a closure disk closing said open end of the casing spaced apart from the charge therein to define a shallow space between the closure disk and the adjacent top surface of the main charge, a priming charge generating a flow of hot gases when ignited disposed at the outside of said closure disk, and a central inlet duct leading from said priming charge into said space for directing the gases generated by said priming charge into said space and into contact with said main charge to ignite the same, said closure disk including several apertures disposed about said inlet duct, whereby said flow of gases is guided through said space along the top surface of the main charge substantially parallel thereto and discharged through said apertures.

2. A device according to claim 1 wherein said casing has a circular cross section and said main charge fills the same at least adjacent to said closure disk, and wherein said disk is a circular disk, said disk apertures defining a concentric ring about said central duct.

3. A device according to claim 2 wherein a reinforcing ring portion overlies the peripheral portion of the disk radially outside of said ring of apertures to reinforce said outer peripheral portion of the disk.

4. A device according to claim 3 wherein the rim at the open end of the casing is beaded over said disk to form said reinforcing ring portion.

5. A device according to claim 1 wherein said duct is in the form of a hollow boss rising from the center of said disk at the outside thereof and in communication with said space, said priming charge being disposed in said hollow boss.

6. A device according to claim 1 wherein the apertures in said closure disk define a concentric ring of circumferentially spaced apertures closely adjacent to the peripheral rim of the disk, and a reinforcing ring overlies the peripheral portion of the disk outside of said ring of apertures, the material of the disk, at least between said apertures, being resistant to the action of the hot gases generated upon ignition of the priming charge and being destroyed by the action of the heat generated upon ignition of the main charge whereby the portion of the disk within said ring of apertures becomes detached from the peripheral disk portion outside of said ring of apertures.

References Cited by the Examiner UNITED STATES PATENTS 1,943,292 1/1934 Babbitt 10235.6 X 2,342,096 2/1944 Zimmerman 102-35.6 2,604,849 7/1952 Frieder et al. 102-35.6 X 2,995,088 8/1961 Asplund 1027O 3,000,311 9/1961 Stanley 10270 BENJAMIN A. BORCHELT, Primary Examiner.

GERALD H. GLANZMAN, Assistant Examiner. 

1. A DEVICE FOR IGNITING THE MAIN CHARGE OF A MISSILE, SAID DEVICE COMPRISING A CASING OPEN AT ONE END AND CONTAINING THE MAIN CHARGE TO BE IGNITED, A CLOSURE DISK CLOSING SAID OPEN END OF THE CASING SPACED APART FROM THE CHARGE THEREIN TO DEFINE A SHALLOW SPACE BETWEEN THE CLOSURE DISK AND THE ADJACENT TOP SURFACE OF THE MAIN CHARGE, A PRIMING CHARGE GENERATING A FLOW OF HOT GASES WHEN IGNITED DISPOSED AT THE OUTSIDE OF SAID CLOSURE DISK, AND A CENTRAL INLET DUCT LEADING FROM SAID PRIMING CHARGE INTO SAID SPACE FOR DIRECTING THE GASES GENERATED BY SAID PRIMING CHARGE INTO SAID SPACE AND INTO CONTACT WITH SAID MAIN CHARGE TO IGNITE THE SAME, SAID CLOSURE DISK INCLUDING SEVERAL APERTURES DISPOSED ABOUT SAID INLET DUCT, WHEREBY SAID FLOW GASES IS GUIDED THROUGH SAID SPACE ALONG THE TOP SURFACE OF THE MAIN CHARGE SUBSTANTIALLY PARALLEL THERETO AND DISCHARGED THROUGH SAID APERTURES. 